Researchers, growers work to prevent E. coli contamination

Friday

In the wake of recent recalls of bagged salad greens tainted with E. coli bacteria, a Wooster microbiologist says consumers can take steps to enhance food safety.

In the wake of recent recalls of bagged salad greens tainted with E. coli bacteria, a Wooster microbiologist says consumers can take steps to enhance food safety.

Less certain is what exactly causes the problem.

“We don’t know yet exactly how it happens,” said microbiologist Jeff LeJeune at Ohio State University’s Ohio Agricultural Research and Development Center. “It can get contaminated from environmental sources, livestock, wildlife or workers.”

LeJeune and his colleagues are working independently and with growers to eliminate the dangers of food-borne pathogens like the E. coli in leafy greens.

This much they do know:

- The dangerous E. coli bacteria attaches itself to specks of soil. That soil may have been contaminated by surface water, sewage, contaminated irrigation water, livestock and wildlife feces or human carriers.

- Although it would take between 1 and 10 million salmonella organisms to make a healthy person sick, E. coli illnesses can arise from exposure to 1,000 organisms.

- As salad greens grow in the field, they may be splashed by contaminated soil during rainfall. Or the greens could be contaminated by the feces of animals, mostly four-stomach ruminants such as cattle, sheep and deer.

- The organism makes its way into the leaf through the plant’s stoma, tiny holes through which it breathes.

Growers work with researchers

LeJeune stressed how diligently growers are in addressing the causes and working with institutions like the research center to enhance food safety.

“Growers are using what we call good agricultural practices, GAPs, and they are a series of scientifically based guidelines that are going to reduce the likelihood that E. coli or other pathogens end up in their foods,” he said.

Four specific areas are targeted and endorsed by the industry and published by the U.S. Food and Drug Administration.

First, water quality constantly must be monitored, both for irrigation and some of the washing steps that are part of commercial production.

Next, sanitation procedures are outlined for the cleaning of processing equipment, trucks and field totes as well as the flumes that wash the greens.

Manure management is the third area of focus. By trying to exclude wildlife from the
crops, unintentional manure application can be controlled.

Government auditors also inspect growers’ fields for contamination.

Time and money

“The industry is not sitting back waiting,” LeJeune said. “They are scrambling to enhance the safety of their product and are investing millions of dollars. And the USDA is investing millions of dollars. The problem is research takes time. Twenty five years ago we didn’t even know what E.coli was. Then we thought it’s a hamburger disease.”

The center is working with Purdue, Michigan State, Kentucky State and others to tweak the GAPs to get a better handle on what is happening.

“How often do you need to test your water? What does the number of coliforms in there mean? If you water fields in the spring and collect crops six to eight weeks later, how much impact does what you did six weeks ago have? Or is it really what happens two weeks before you harvest? OARDC is in a unique position because I get to partner with horticulture and crop science and plant pathology but I can’t emphasize enough that producers are on board.